This application relates generally to adjustable chairs, and more particularly to height adjustment mechanisms used with adjustable chairs.
Office chairs typically include a chair back, a chair seat, and a base that supports the chair. The chair back is coupled to the chair seat, and the chair seat is coupled to the chair base. More specifically, a column extends between the base and the chair seat to support the chair seat. At least some known chair bases include casters or glides that enable the chair base to be in freely-rollable or freely-glidable contact with a floor.
Sitting in a chair at an improper height for prolonged periods of time may increase the discomfort and fatigue to the occupant. To facilitate improving a comfort level of seated occupants, at least some chairs include chair backs including adjustment mechanisms that permit the chair back to be variably positioned with respect to the chair seat, and permit the chair seat to be variably positioned with respect to the chair base. More specifically, at least some known chairs include an adjustable column that permits a user to vary a height of the chair seat relative to the chair base.
At least some known adjustable columns are coupled to the chair seat with threaded connections. The threaded connections permit the chair seat to rotate to adjust the relative height of the seat. As a result, when an occupant rotates the chair seat relative to the chair base, the height of the seat relative to the floor is changed.
To permit rotation of the chair seat without adjustments being made to the relative height of the chair, at least some other known adjustable columns are rotatably coupled to the chair base with swivel fixtures that permit the chair seat to rotate without changing the height of the chair relative to the floor. Such columns also include pneumatic cylinders which permit the relative height of the chair to be manually changed. However, often the adjustments can not be made while the occupant is seated, and as a result, an adjustment process can be time-consuming and tedious as the occupant must often make numerous trial adjustments finding a chair seat position that is at a height relative to the floor that is comfortable to the occupant.
In an exemplary embodiment, a height adjustment mechanism for a chair enables a height of a chair seat relative to a chair base to be adjusted electrically in a cost effective and reliable manner. The height adjustment mechanism includes an electric motor, an upper enclosure member, a lower enclosure member, and a limit switch. The lower enclosure member is coupled to the upper enclosure member, and the electric motor is coupled to at least one of the upper and lower enclosure members to telescopically move at least one of the upper and lower enclosure members relative to the remaining enclosure member. The limit switch is electrically coupled to the electric motor to limit an amount of telescopic movement of at least one of the upper and lower enclosure members.
During use, a seated occupant may engage a control switch to electrically raise or lower the chair seat relative to the chair base. When the electric motor is activated, a drive shaft coupled to the electric motor through a gear box threadingly engages at least one of the upper and lower enclosure members to cause that member to rotate, thus raising or lowering the chair seat, depending upon a direction of rotation of the electric motor. As a result, the height adjustment mechanism permits selective adjustments of the height of the chair seat by a fully-seated occupant in a cost-effective and reliable manner.